RESUMO
It is of great importance and worthy of efforts to give a clear structure-property relationship and microscopic mechanism of fluorescence emitters with high quantum yield. In this work, we perform a detailed computational investigation to give an explanation to the high efficiency of a fluorescence emitter XBTD-NPh based TADF sensitized fluorescence (TSF) OLEDs, and construct a symmetry structure DSBNA-BTD. Theoretical calculations show that XBTD-NPh is a long-time phosphorescent material at 77 K and TADF is attributed to the RISC of T1 to S1 state. For DSBNA-BTD, excitons arrived at T1 state comes to a large rate of nonradiatively path to the ground state, meaning it is may not be an efficient TADF molecule. For both molecules, the fast IC between T2 and T1 state results in that the hot exciton channel T1-Tn-S1 makes no contribution to the TADF.
RESUMO
The donor-acceptor interface plays a critically important role in determining the power conversion efficiency of organic solar cells via controlling charge separation (CS) and recombination (CR) processes. Here, we combine the electronic structure calculations with electron transfer rate theory to clarify the CS and CR processes in ThQs-C60 /PDIxCN2 donor-acceptor complexes. The results reveal that in ThQs-PDIxCN2 the CS comes from both the dissociations of photo-induced singlet exciton and singlet fission-induced triplet exciton with a high efficiency, whereas in ThQs-C60 only the singlet exciton dissociation can take place because the triplet exciton lies below the charge-transfer exciton. However, very high CR rates in ThQs-PDIxCN2 obliterate the benefit of fast CS, inversely leading to the ThQ-C60 complex with a better cell efficiency. The present results are consistent with experimental observation and may furnish a possible patten to improve the overall conversion efficiency. © 2018 Wiley Periodicals, Inc.
RESUMO
A novel method has been developed to prepare hydrogenated graphene (HG) via a direct synchronized reduction and hydrogenation of graphene oxide (GO) in an aqueous suspension under (60)Co gamma ray irradiation at room temperature. GO can be reduced by the aqueous electrons (e(aq)(-)) while the hydrogenation takes place due to the hydrogen radicals formed in situ under irradiation. The maximum hydrogen content of the as-prepared highly hydrogenated graphene (HHG) is found to be 5.27 wt% with H/C = 0.76. The yield of the target product is on the gram scale. The as-prepared HHG also shows high performance as an anode material for lithium ion batteries.
